A study led by the URV has demonstrated that virgin olive oil enriched with its own polyphenols and with those from thyme protects the DNA from oxidation. When these two types of polyphenol are added to olive oil (or indeed any other product) they decrease the risk of DNA damage, which can affect the metabolism and cell reproduction and lead to pathologies such as cancer, among other negative consequences

The study, led by scientists from the Pharmacology Unit and the Lipids and Arteriosclerosis Research Unit of the URV, found that consuming virgin olive oil enriched with olive and thyme polyphenols protects the organism from oxidation caused by pollution, tobacco and certain foods.

These oxidants can cause an imbalance between the organism’s antioxidant and the pro-oxidant systems. Olive oil enriched with a mixture of olive and thyme polyphenols helps to tip the balance back in favour of the antioxidant system and thus prevent the onset of oxidation.

Polyphenols, the crucial antioxidant

Polyphenols are natural substances found in plants, fruit, vegetables, coffee and chocolate. They protect plants from oxidation and, thanks to their characteristics, act as antioxidants and anti-inflammatories in people. They are not essential nutrients in the diet, but individuals who do not ingest them can become ill.

The research was conducted on individuals with levels of LDL cholesterol, known as ‘bad cholesterol’, that were slightly high but not sufficiently so to warrant treatment with drugs. Randomly divided into three groups, the volunteers consumed normal oil, virgin olive oil enriched with olive polyphenols and virgin olive oil enriched with a mixture of olive polyphenols and thyme polyphenols. Both enriched olive oils had the same quantities of polyphenols but with different compositions to enable the researchers to determine the combined effect on biological functions.

Thyme was chosen because it is one of the most common aromatic herbs used in the Mediterranean region and is regarded as having various health benefits. After the volunteers had consumed the oils, the researchers found that the thyme polyphenols were most easily absorbed by the body, making this a possible reason why the best results were obtained with oil containing thyme.

The positive results from the research have led to the conclusion that olive oil enriched with thyme can act as another functional food for protecting health. On the basis of the research, health recommendations can be made to the general public and in particular to people with high levels of bad cholesterol.

Enriching with polyphenols to strengthen the effects

Of the three oils that were tested, the most effective virgin olive oil for protecting DNA was the one enriched a mixture of olive and thyme polyphenols. The resulting oil contains more polyphenols than are normally found in common olive oil thanks to a technological process in which the polyphenols are first extracted from the orujo (the wet solid waste produced by pressing olives rich in polyphenols) and then added to the oil. This allows individuals to consume more olive polyphenols without exceeding the daily recommended intake of olive oil.

The same process is used to add polyphenols extracted from thyme, carefully controlling the quantity to ensure that they do not negatively affect flavour of the resulting oil.

Polyphenols in capsules?

The study experimented with the stable addition of polyphenols to virgin olive oil. However, these polyphenols are water soluble, which means they can be added to other products such as fruit juices or even to capsules for direct consumption. In fact, this is idea has already been suggested to the researchers by a company interested in the health benefits deriving from the research.

In the same vein, other studies carried out on these oils have shown that they can improve endothelial function, a marker for arteriosclerosis. Researchers are now engaged in trying to determine the polyphenols’ acting mechanisms by investigating which proteins help protect the arteries and increase their ability to dilate and prevent heart disease, the biggest cause of death in the Western world.

The research was led by the URV researchers Marta Romeu, Vanessa Sánchez and Montserrat Giralt from the Pharmacology Unit of the Department of Basic Medical Sciences; Laura Rubió, Rosa M. Valls, Anna Pedret, Úrsula Catalán and Rosa Solà from the URV’s Lipids and Arteriosclerosis Research Unit, and Rosa Ras from the Centre for Omic Sciences of the URV. Also participating were María del Carmen López de las Hazas and María J. Motilva from the Agrotecnio research centre of the University of Lleida, and Olga Castañer, Rafael de la Torre and Montserrat Fitó from the Hospital del Mar Medical Research Institute (IMIM) in Barcelona.

Reference: Marta Romeu, Laura Rubió, Vanessa Sánchez-Martos, Olga Castañer, Rafael de la Torre, Rosa M. Valls, Rosa Ras, Anna Pedret, Úrsula Catalán, María del Carmen López de las Hazas, María J. Motilva, Montserrat Fitó, Rosa Solà and Montserrat Giralt: Virgin Olive Oil Enriched with Its Own Phenols or Complemented with Thyme Phenols Improves DNA Protection against Oxidation and Antioxidant Enzyme Activity in Hyperlipidemic Subjects. Journal of Agricultural and Food Chemistry. February 2016. DOI: http://pubs.acs.org/doi/abs/10.1021/acs.jafc.5b04915